Balloon Launch from San Andreas

by David Voit – WB6TOU

Our latest balloon was launched this morning (April 25th, 2025) at 11:30 am from San Andreas, CA. After six hours, it has crossed the Sierra Nevada mountains cruising at 77 mph headed east over western Nevada at 39,000 feet .

These high resolution pictures are available to download at Keith Colgan Photography

The balloon was built using a nylon/polyethylene party balloon sold by Yokohama Balloon Co. The lifting gas is hydrogen. It should eventually float at about 41,000 feet and travel with the wind.

The radio beacon is sold by QRP Labs in Turkey. It transmits in the 20 meter amateur radio band with a power of only 20 mW. It is powered by solar panels assembled in a triangular pyramid so the sun is always shining on one of the panels. The weight, including antenna, is 26 grams. Its amateur radio call sign is N6FRG for the Calaveras Radio Club.

The beacon is programmed to transmit data every 10 minutes using the Weak Signal Propagation Reporter operated by the Physics Department at Princeton. Receiving stations around the world monitor WSPR signals and report its path, speed and altitude.

To watch its progress, go to https://lu7aa.org/wsprx.asp . Find the call sign N6FRG (listed with other call signs in very small letters at the top of the page) and click on it. Then wait for the data to download and for the map to be displayed.

There are some great science projects possible using the data sent down by one of these balloons. They can stay aloft for over a year, but they always come down, usually from thunderstorms. If you have a question or want to discuss a personal project, contact me at dvoit@alum.mit.edu .